The lab plays a crucial role in ensuring environmental safety at
the toxic landfill.

According to a letter dated in May of 2010, U.S. EPA regulators
are concerned about the lab's environmental test results. In the
letter, EPA officials claim the lab has a history of "poor quality
control."

The letter goes on to say that unreliable test results could
lead the company to violate state hazardous waste requirements. EPA
began looking at the facility after test results provided by
Chemical Waste, a subsidiary of Waste Management, did not match the
EPA's findings.

A Waste Management spokeswoman declined to give recorded
comment, instead issuing an email statement. Waste Management's
Jennifer Andrews says the company is fully cooperating with
investigators.

The EPA strongly suggested in the letter the company should halt
lab testing until the investigation is complete. Waste Management
has not used the facility since then. Currently a third part vendor
is doing the lab work.

"We have confidence in our lab and await the ok to resume using
it," Andrews writes.

Greenaction's Bradley Angel is a critic of Waste Management.
Angel questions the company's claims that it works closely with
regulators to comply with environmental rules.

"Because, if you look at the big picture, there's an
investigation about their lab results. How does that jive with the
fact that Chem Waste has a long and well documented history of
enforcement actions by the EPA against them?," Bradley asks.

"People should be concerned," he adds.

On Thursday, Waste Management released a study showing PCBs and other dioxin
like substances from the facility pose little risk to human
health.

The EPA stressed the investigation into the lab is in no way
connected to that study.